Correct Option (3)
The schedule for the guest lectures can be determined by systematically applying the given constraints:
- The constraint "Guest faculty for History is available only on Tuesday" directly establishes that History must be scheduled on Tuesday.
- The conditions "Mathematics lecture has to be scheduled immediately after the day of Economics lecture" and "English lecture has to be scheduled immediately before the day of Economics lecture" imply a fixed sequence of three lectures: English - Economics - Mathematics. This block requires three consecutive days.
- Considering that Tuesday is occupied by History, the only remaining block of three consecutive days in the week (Monday to Friday) is Wednesday, Thursday, Friday.
- Therefore, the English - Economics - Mathematics block must be scheduled as:
- Wednesday: English
- Thursday: Economics
- Friday: Mathematics
- This arrangement also satisfies the condition that Economics cannot be scheduled on Tuesday.
- With History on Tuesday and the English-Economics-Mathematics sequence occupying Wednesday, Thursday, and Friday, the only remaining day is Monday and the only remaining subject is Statistics. Thus, Statistics is scheduled on Monday.
The complete schedule is:
- Monday: Statistics
- Tuesday: History
- Wednesday: English
- Thursday: Economics
- Friday: Mathematics
Based on this schedule, Mathematics is the last lecture in the week, scheduled on Friday.
Incorrect Options:
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History: History is scheduled on Tuesday, as per the explicit availability constraint, making it an early lecture in the week, not the last.
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English: English is scheduled on Wednesday, immediately preceding Economics, and thus cannot be the last lecture.
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Economics: Economics is scheduled on Thursday, between English and Mathematics, and therefore is not the last lecture of the week.